1. Technical Field
The present disclosure relates to valve assemblies of the type adapted to allow the introduction of a surgical instrument into a patient""s body. In particular, the disclosure relates to a valve assembly to be used in combination with a cannula assembly where the cannula assembly is intended for insertion into a patient""s body and an instrument is inserted into the patient""s body through the cannula.
2. Background of Related Art
Laparoscopic procedures are performed in the interior of the abdomen through a small incision, e.g., through narrow endoscopic tubes or cannulas inserted through a small entrance incision in the skin. Minimally invasive procedures are performed elsewhere in the body, e.g., in the chest, and are often generally referred to as xe2x80x9cendoscopicxe2x80x9d procedures. Minimally invasive or endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e. provisions must be made to ensure that gases do not enter or exit the body through the endoscopic incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, endoscopic procedures often require the surgeon to act on organs, tissues, and vessels far removed from the incision, thereby requiring that any instruments used in such procedures be relatively long and narrow.
For such procedures, the introduction of a tube into certain anatomical cavities such as the abdominal cavity is usually accomplished by use of a system incorporating a trocar and cannula assembly. A cannula assembly is formed of a cannula attached to a cannula housing which generally includes valve assembly adapted to maintain a seal across the opening of the valve assembly both with and without an instrument inserted therethrough. Since the cannula is in direct communication with the internal portion of the valve assembly, insertion of the cannula into an opening in the patient""s body so as to reach the inner abdominal cavity should be adapted to maintain a tight interface between the abdominal cavity and the outside atmosphere.
Since minimally invasive surgical procedures in the abdominal cavity of the body generally require insufflating gases to raise the cavity wall away from vital organs, the procedure is usually initiated by use of a Verres needle through which a gas is introduced into the body cavity. The gas provides a slight pressure which raises the wall surface of the peritoneum away from the vital organs thereby providing an adequate region in which to operate. Thereafter, a trocar assembly which includes a cannula and a trocar or obturator is inserted within the cannula to puncture the peritoneum, i.e. the inner lining of the abdominal cavity wall. The obturator is removed and laparoscopic or endoscopic surgical instruments may then be inserted through the cannula to perform surgery within the abdominal cavity. The cannula may also be utilized for introducing tubes into the body as for drainage purposes, for specimen removal, for diagnostic evaluations, or the like.
In view of the need to maintain the atmospheric integrity of the inner area of the cavity, a valve assembly for a cannula which permits introduction of an obturator and a wide range of surgical instruments and which maintains the atmospheric integrity of the inner area of the cavity is desirable. Generally, in the context of insufflatory, minimally invasive surgical procedures, cannula assemblies include structure(s) that satisfy two sealing requirements. The first requirement is to provide a tight seal when an instrument is not present in the cannula. The second requirement is to provide a tight seal when an instrument is being introduced into or already is present in the cannula In this regard, there have been a number of attempts in the prior art to provide such sealing requirements.
A disadvantage of several known valve assemblies for cannulas, however, concerns the difficulty encountered in inserting and advancing the surgical instrument through the valve unit. In particular, since known elastomeric seal members are designed to form and maintain a tight seal about the instrument, the aperture or slit within the seal through which the instrument is passed is of relatively small or narrow dimension. Further, portions of the valve member defining the aperture are generally thick in cross-section to provide a sufficient closing force of the seal about the instrument. As a consequence of some of these design considerations, the level of force needed to insert and advance the instrument through the seal aperture is increased, thereby requiring awkward maneuvering on the surgeon""s behalf to appropriately position the instrument for the desired surgery. Moreover, some known valve assemblies are generally ineffectual in accommodating instruments of differing diameter while maintaining acceptable insertion forces and facilitating the range of desired surgical manipulations, e.g., angular instrument movements and specimen removal.
Accordingly, a need exists for an improved valve unit or cannula assembly which is capable of forming and maintaining a seal about instruments of varying diameters inserted through the cannula and which incorporates structure to enhance and facilitate passage of the instrument through the valve unit.
The present invention obviates the disadvantages of the prior art by providing a valve unit or assembly for a cannula assembly. Generally stated, the present disclosure is directed to a valve assembly for sealed reception of an elongated object. The assembly includes a valve body defining at least one opening configured and dimensioned to permit entry of an elongated object and defining a central longitudinal axis, and an elongated seal member having a resilient sealing structure and defining an aperture in general alignment with the opening of the valve body whereby the aperture is configured and dimensioned such that upon insertion of the object into the aperture, the resilient sealing structure resiliently engages the outer surface of the object in a tight manner. The sealing structure includes a plurality of elongated bristle members attached to the seal member. The bristle members are positioned to engage the elongated object upon at least partial insertion of the elongated object into the valve body. Each bristle member is adapted to be displaced relative to the longitudinal axis to facilitate expansion of the aperture of the seal member upon entry of the elongated object therein.
In a preferred embodiment, the valve assembly includes a valve body defining a longitudinal opening configured and dimensioned to permit entry of an elongated object, an elongated resilient seal member at least partially positioned within the valve body and defining an aperture to permit entry of the elongated object therein in a tight manner and a plurality of bristle members attached to the seal member and concentrically arranged about the central longitudinal axis of the valve body. The plurality of bristle members are positioned to engage the elongated object upon insertion of the elongated object within the valve body and are adapted to be displaced upon introduction of the elongated object to engage portions of the seal member defining the aperture to expand the aperture.
The bristle members of this embodiment are preferably linearly mounted on a substrate and extend generally perpendicularly with respect to the inner surface of the seal member. Upon entry of the elongated object, the bristle members simultaneously pivot downwardly to uniformly open or expand the aperture.
The valve assembly is intended to be used in combination with a cannula including a cannula housing and a cannula sleeve extending distally from the cannula housing and is preferably detachably connected to the cannula housing. The cannula housing may include a valve member disposed therein which is moveable between a substantially closed position in the absence of an instrument to an open position in the presence of an instrument.